Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...
[sfrench/cifs-2.6.git] / Documentation / admin-guide / kernel-parameters.txt
index 84bac92f2cfae6c19d71ab5d03751a01fc16ee59..520dedae715088322a2b3b3bd8a4b3736a1ded45 100644 (file)
                        Note that using this option lowers the security
                        provided by tboot because it makes the system
                        vulnerable to DMA attacks.
+               nobounce [Default off]
+                       Disable bounce buffer for unstrusted devices such as
+                       the Thunderbolt devices. This will treat the untrusted
+                       devices as the trusted ones, hence might expose security
+                       risks of DMA attacks.
 
        intel_idle.max_cstate=  [KNL,HW,ACPI,X86]
                        0       disables intel_idle and fall back on acpi_idle.
                          synchronously.
 
        iommu.passthrough=
-                       [ARM64] Configure DMA to bypass the IOMMU by default.
+                       [ARM64, X86] Configure DMA to bypass the IOMMU by default.
                        Format: { "0" | "1" }
                        0 - Use IOMMU translation for DMA.
                        1 - Bypass the IOMMU for DMA.
 
        machvec=        [IA-64] Force the use of a particular machine-vector
                        (machvec) in a generic kernel.
-                       Example: machvec=hpzx1_swiotlb
+                       Example: machvec=hpzx1
 
        machtype=       [Loongson] Share the same kernel image file between different
                         yeeloong laptop.
                        Run specified binary instead of /init from the ramdisk,
                        used for early userspace startup. See initrd.
 
+       rdrand=         [X86]
+                       force - Override the decision by the kernel to hide the
+                               advertisement of RDRAND support (this affects
+                               certain AMD processors because of buggy BIOS
+                               support, specifically around the suspend/resume
+                               path).
+
        rdt=            [HW,X86,RDT]
                        Turn on/off individual RDT features. List is:
                        cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,